Fluid delivery device identification and loading system

ABSTRACT

A medical pump includes a chassis having a fixed seat, and a main carriage having a carriage footing for receiving a fluid delivery device and restricting its movement. An actuator automatically moves the main carriage between open and closed positions to engage the fluid delivery device to the seat. The seat establishes the position of both the main carriage and fluid delivery device in the closed position. The actuator is connected to the main carriage by a rear carriage assembly having a manual release element for disengaging the actuator from rear carriage assembly and thereby from the main carriage. A processing unit detects jam conditions by processing carriage position data and electrical load data from the actuator.

BACKGROUND OF THE INVENTION

The present invention relates to a means of automatically loading andunloading a pump cassette or other fluid delivery device into a medicalpump.

Modern medical care often involves the use of medical pump devices todeliver fluids and/or fluid medicine to patients. Medical pumps permitthe controlled delivery of fluids to a patient, and such pumps havelargely replaced gravity flow systems, primarily due to the pump's muchgreater accuracy in delivery rates and dosages, and due to thepossibility for flexible yet controlled delivery schedules. Of themodern medical pumps, those incorporating a diaphragm cassette are oftenpreferred because they provide more accurately controlled rate andvolume than do other types of pumps.

A typical positive displacement pump system includes a pump devicedriver and a fluid delivery device, including but not limited to asyringe, tubing, section of tubing, or a disposable cassette. Thedisposable cassette, which is adapted to be used only for a singlepatient and for one fluid delivery cycle, is typically a small plasticunit having an inlet and an outlet respectively connected throughflexible tubing to a fluid supply container and to the patient receivingthe fluid. The cassette includes a pumping chamber, with the flow offluid through the chamber being controlled by a plunger or plungeractivated in a controlled manner by the device driver.

One of the requirements for many pumps, including cassette pumps, isthat they are able to dictate the proper positioning of the fluiddelivery device or cassette when loaded. The proper positioning of thecassette is critical to ensure that any pump elements (including theplunger and/or sensors) that interact with the cassette are preciselyaligned and positioned to accurately produce the desired output of thecassette or sense conditions related to the pump.

Previous pumps attempted to accomplish the proper positioning of thecassette by providing a molded seat that a user would manually push thecassette into. Once the cassette is forced into the molded seat,retentive snap elements engage the outer surface of the cassette to holdthe cassette within the molded seat.

These previous pumps often have few if any physical elements to ensureproper cassette orientation to the pump. They also do not ensure properand complete seating of the cassette to the pump. Additionally, theyhave insufficient means for monitoring if the cassette was indeedoriented correctly and/or fully seated to the pump.

Therefore, a principal object of this invention is to provide a medicalpump having an automated loading system with improved positioning of thefluid delivery device.

A further object of the invention is to provide a medical pump thatmonitors proper fluid delivery device loading.

Another object of the invention is to provide a medical pump having anindicator window for indicating channel conditions.

A still further object of the invention is to provide a medical pumphaving an illumination element for illuminating a main carriage areawhere the fluid delivery device is loaded.

Another object of the invention is to provide a medical pump having amanual release element for manually ejecting a fluid delivery devicefrom the pump.

These and other objects will be apparent to those skilled in the art.

SUMMARY OF THE INVENTION

A medical pump includes a chassis having a fixed seat, and a maincarriage having a carriage footing for receiving a fluid deliverydevice, including but not limited to a cassette, syringe and/or tubing,and restricting its movement. An orientation sensor determines thecorrect insertion of the fluid delivery device in the carriage. Anindicator window includes an illumination element for illuminating amain carriage area and a multicolor indicator element for illuminatingthe indicator window. An actuator automatically moves the main carriagebetween open and closed positions to engage the cassette to the fluiddelivery device seat. The seat establishes the position of both the maincarriage and fluid delivery device in the closed position. The actuatoris connected to the main carriage by a rear carriage assembly having amanual release element for disengaging the actuator from rear carriageassembly and thereby from the main carriage. A processing unit detectsjam conditions by processing carriage position data and electrical loaddata from the actuator.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of the medical pump of the present invention;

FIG. 2 is an exploded perspective view of an infuser mechanism of thepresent invention;

FIG. 3 is an exploded perspective view of an indicator window of thepresent invention;

FIG. 4 is a rear perspective view of an indicator window of the presentinvention;

FIG. 5 is a perspective view of a cassette for use with the presentinvention;

FIG. 6 is a left side perspective view of an open loader with nocassette;

FIG. 7 is a left side perspective view of a closed loader with acassette;

FIG. 8 is a perspective exploded left side view of a front carriageassembly of the present invention;

FIG. 9 is a perspective left side view of the pump chassis assembly;

FIG. 10 is a partial sectional left side perspective view of an openloader with no cassette taken along line 10-10 in FIG. 6, where the leftslide assembly is removed and the carriage is in vertical cross section;

FIG. 11 is a partial sectional left side perspective view similar toFIG. 10, but a cassette is in the open loader;

FIG. 12 is a partial sectional left side perspective view of a closedloader with no cassette taken along line 12-12 in FIG. 7, where the leftslide assembly is removed and the carriage is in vertical cross section;

FIG. 13 is a partial sectional left side perspective view similar toFIG. 12, but a cassette is in the closed loader;

FIG. 14 is a perspective left side view of a manual release, actuatorassembly and infuser board;

FIG. 15 is an exploded perspective right side view of the left and rightchassis substrate;

FIG. 16 is a vertical cross sectional side view of the loader in theclosed position with a cassette loaded in it;

FIG. 17 is a vertical cross sectional side view of the loader having theemergency released engaged with the actuator assembly so that therelease plate is raised;

FIG. 18 is a vertical cross sectional side view of the loader where theactuator assembly is disengaged;

FIG. 19 is a vertical cross sectional side view of the loader where theactuator assembly is disengaged and the manual release is returned toits home position;

FIG. 20 is a vertical cross sectional side view of the loader where themanual release is pulled forward and the actuator driven forward so thatthe release plate is raised for reengaging the actuator assembly;

FIG. 21 is a schematic diagram of the medical pump of the presentinvention, illustrating the functional components of the pump and thecassette; and

FIG. 22 is a perspective exploded left side view of another embodimentof the front carriage assembly of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIG. 1, a medical pump 10 is shown having a housing 12and an infuser mechanism 14 attached to the housing 12. The infusermechanism 14 includes an infuser cover 16, an indicator window 18attached to the infuser cover 16, and a loader 20 for a fluid deliverydevice, including but not limited to a cassette, syringe, and/or tubing.The loader 20 is attached to the infuser cover 16 immediately below theindicator window 18.

With reference to FIG. 2, indicator opening 22, loader opening 24, andmanual release opening 26 are all formed in the infuser cover 16. Theindicator opening 22 permits insertion and attachment of the indicatorwindow 18 to the infuser cover 16. Likewise, the loader opening 24permits insertion and attachment of the loader 20 to the infuser cover16. The manual release opening 26 permits insertion and attachment of amanual release portion 28 of the loader 20 to the infuser cover 16.

With reference to FIGS. 3 and 4, a window body 30 and light assembly 32form the indicator window 18. The window body 30 is formed of atransparent or translucent material which facilitates the diffusion andtransmission of light therethrough. The window body 30 has an outersurface 34 that includes a groove shaped portion 36. The groove shapedportion 36 is shown as being concave, but may be formed in any suitableshape. The groove shaped portion 36 provides clearance for a user tosmoothly route an inlet tube (not shown) to the loader 20.

A pair of rails 38 extends horizontally from an inner surface of thewindow body 30. The rails 38 secure the light assembly 32 to the windowbody 30. Several multi-color indicator elements 42 are located on theupper surface of the light assembly 32. These indicator elements 42 areshown as three individual light-emitting diode (LED) lights. Theindicator elements 42 are each associated with corresponding light pipes44.

The light pipes 44 are formed as an integral portion of the innersurface 40 of the window body 30. The light pipes 44 facilitate the evendistribution of light from the indicator elements 42 to the outersurface 34 of the window body 30. Due to the multi-color attributes ofthe indicator elements 42, the outer surface 34 of the window body 30can be lit up with various colors, and can continuously orintermittently be lit. The coloring and/or flashing is used to providean indication of the operation conditions of the pump 10.

One or more illumination elements 46 are located on the lower surface ofthe light assembly 32. These illumination elements 46 are shown as twoindividual white light LEDs. When the loader 20 is opened for insertionof a cassette, the illumination elements 46 are activated to illuminatethe area where the cassette is inserted into the pump 10. Theillumination elements 46 may immediately light up or may be designed togradually illuminate upon opening of the loader 20. The determination ofwhen the loader 20 has been opened will be discussed in greater detailbelow.

Several snap fasteners 48 extend from the inner surface 40 of the windowbody 30. These snap fasteners 48 secure the indicator window 18 to theinfuser cover 16 in covering relation to the indicator opening 22.

With reference to FIG. 5, one fluid delivery device, such as a cassette50, suitable for use with the present invention is shown. The cassette50 includes an inlet 52 and an outlet 54 formed in main body 56.Attached to the outlet 54 is a tube support element 58 for ensuring thattubing (not shown) connected to the outlet 54 is maintained in a properposition with respect to external sensors (not shown).

An elastomeric membrane 60 forms an inlet diaphragm 62, an outletdiaphragm (generally indicated at 64, but only shown in FIG. 21), and apumping chamber 66 located between the inlet and outlet diaphragms 62and 64 on an inner face 68 of the main body 56.

In operation, fluid enters through the inlet 52 and is forced throughoutlet 54 under pressure. The fluid is delivered to the outlet 54 whenthe pump 10 displaces the pumping chamber 66 to expel the fluid. Duringthe intake stroke the pump 10 releases the pumping chamber 66, and thefluid is then drawn through the inlet 52 and into the pumping chamber66. In a pumping stroke, the pump 10 displaces the pumping chamber 66 toforce the fluid contained therein through the outlet 54. Thus, the fluidflows from the cassette 50 in a series of spaced-apart pulses ratherthan in a continuous flow. The fluid is delivered to the patient at apre-set rate, in a pre-determined manner, and only for a particularpre-selected time or total dosage.

A flow stop 70 is formed as a switch in the main body 56 and protrudesfrom the inner surface 68. This protrusion forms an irregular portion ofthe inner surface 68 which can be used to align the cassette 50 as wellas monitor the orientation of the cassette 50, as will be discussedfurther below. The flow stop 70 provides a manual switch for closing andopening the cassette 50 to fluid flow.

A rim 72 is located around the outer surface of the main body 56 andadjacent the inner surface 68. The rim 72 is used to secure the cassettein a fixed position relative to the pump 10.

With reference to FIGS. 5 and 6, a front carriage assembly 74 is shownextending from the loader 20. In this extended position, a cassette 50(not shown) is inserted into a top opening 76 of the front carriageassembly 74.

With reference to FIGS. 5 and 7, the front carriage assembly 74 is shownin a closed position. In proper use, top opening 74 first receives theoutlet 54 of the cassette 50 with the inner surface 68 facing towardsthe loader 20. This proper orientation of the cassette 50 to the loader20 is essential for proper operation of the pump 10. As will bedescribed in more detail below, the loader 20 of the present inventionhas been designed to include several mechanical and electronic featuresto ensure the proper alignment of the cassette 50.

With reference to FIGS. 5 and 8, a main carriage 78 having a main body80 with a top opening 81 therein for receiving a cassette 50 as well asan open base surface 82 which permits access to the inner surface 68 ofthe cassette 50. Left and right vertical side walls 84 and 86 extendhorizontally from the base surface 82. Outer lips 88 are positionedopposite the base surface 82 on the end of each side wall 84 and 86. Theouter lips 88 define an outer opening 90 in the main body 80. The outerlips 88 abut the rim 72 of an inserted cassette 50 to prevent thecassette 50 from falling out of the outer opening 90, and also enablethe main carriage 78 to press the cassette 50 towards the loader 20 byengaging the rim 72.

A cassette footing 92 is formed from portions of the side walls 84 and86 and the outer lips 88. The cassette footing 92 restricts movement ofthe cassette 50 within the main carriage 78 to hold the cassette 50 in adesired position with respect to the loader 20. A lateral support 94 isformed in each side wall 84 and 86 for receiving the rim 72 andrestricting the lateral movement of the rim 72. An inner lip 95 isformed in each side wall 84 and 86 for restricting the horizontalmovement of the inner surface 68 by engaging the rim 72. A lower support96 is formed between the side walls 84 and 86 to support the cassette 50in the main carriage 78. An outlet support lip 98 is formed at the lowerend of outer opening 90 to fit around and restrict the movement of thecassette outlet 54.

The front carriage assembly 74 includes left and right front fascia 102and 104 that hold the main carriage 78 and attach the main carriage 78to the rest of the loader 20. Each front fascia 102 and 104 has a mainbody 106 with a side opening 108 for receiving the main carriage 78therein.

With reference to FIGS. 5, 6 and 8, the front fascia 102 and 104 formopenings which correspond to matching openings in the main carriage 78.Thus the front fascia 102 and 104 has outer opening 114, inner opening116, and defines the top opening 76. The outer opening 114 adjoins theouter opening 90 of the main carriage 78 and permits a user to see thata cassette 50 is contained within the front carriage assembly 74. A tubesupport opening 115 is formed at the lower end of outer opening 114 tofit around and restrict the movement of the tube support 58. The inneropening 116 adjoins open base surface 82 and permits access to the innersurface 68 of the cassette 50.

With reference to FIG. 9, a pump chassis assembly 120 is shown. The pumpchassis assembly 120 has a main chassis 122 with a vertically disposedbase surface 124. The base surface 124 has an opening 126 permitting aninlet pressure sensor 128 to pass through the base surface 124 andextend horizontally therefrom. An opening 130 in the base surface 124 ispositioned below the inlet pressure sensor 128 and permits an outletpressure sensor 132 to pass through the base surface 124 and extendhorizontally therefrom. An opening 134 in the base surface 124 ispositioned between the inlet pressure sensor 128 to and the outletpressure sensor 132 and permits a plunger 136 to pass through the basesurface 124 and extend horizontally therefrom. A motor 142 is connectedto the plunger 136 for driving (or reciprocating) the plunger back andforth.

An opening 138 in the base surface 124 is positioned below the outletpressure sensor 132 and permits an orientation sensor 140 to passthrough the base surface 124 and be positioned flush with the basesurface 124. The orientation sensor 140 is shown as an infraredreflective sensor which determines the distance to the cassette 50. Theorientation sensor 140 is located to detect the presence or absence offlow stop 70 as an irregular portion of the inner surface 68. Thedetection of the presence or absence of flow stop 70 is used to alignthe cassette 50 as well as monitor the orientation of the cassette 50.

With reference to FIGS. 5, 9 and 13, once a cassette 50 is fully loadedand the front carriage assembly 74 is closed, the inlet pressure sensor128 engages the inlet diaphragm 62 of cassette 50. The outlet pressuresensor 132 engages the outlet diaphragm 64. The plunger 136 engages thepumping chamber 66. A flow stop post 143 positioned between the outletpressure sensor 132 and the orientation sensor 140 on the base surface124 engages and closes the flow stop 70 by forcing the flow stop 70 to aclosed position. The flow stop post 143 prevents free flow of fluidthrough cassette 50 once the front carriage assembly 74 is closed.

With reference to FIGS. 8 and 9, one embodiment of the present inventionis shown with a pair of air sensors 144 including sensor heads 145attached to the near ends of arms 146. The arms 146 are pivotallysecured to the base surface 124 at hinge 148. The arms 146 are springbiased to pull the air sensors 144 together. A cam element 150 extendshorizontally from the far end of each arm 146.

An air sensor slot 152 is formed in each front fascia 102 and 104 toreceive the near ends of arms 146 as the front carriage assembly 74moves in and out with respect to the main chassis 122. Air cam plates154 extend horizontally from each front fascia 102 and 104 to engage anddrive the cam elements 150 of the air sensors 144.

When the front carriage assembly 74 is fully extended, an open portion156 of each air cam plate 154 forces the cam elements 150 inward,pivoting the arms 146 about the hinges 148 and moving the sensor heads145 apart. When the front carriage assembly 74 is fully withdrawn, aclosed portion 158 of each air cam plate 154 allows the spring biasedcam elements 150 to move outward, pivoting the arms 146 about the hinges148 and moving the sensor heads 145 together. A ramp portion 160 of eachair cam plate 154 is located between the open portion 156 and the closedportion 158 of each air cam plate 154 for providing a smooth transitionfor the cam element 150 as it moves from the open portion 156 to theclosed portion 158.

The outward movement of the sensor heads 145 is required to alloweffluent tubing (not shown) attached to the cassette outlet 54 to bereceived between the sensor heads 145. The inward movement of the sensorheads 145 is required to press the sensor heads 145 together to squeezethe effluent tubing (not shown). This squeezing is necessary for thesensor heads 145 physically contact the effluent tubing (not shown) toget accurate measurements of air contained therein.

With reference to FIGS. 8, 9 and 12, a fixed seat 162 is formed bymultiple finger elements 164, 166, 168, and 170 extending horizontallyfrom the vertical base surface 124. The bottom finger element 164 ispositioned below the orientation sensor 140 and receives the cassetteoutlet 54 to restrict the movement of the inlet 54. The top fingerelement 166 is positioned above the inlet pressure sensor 128 and has anouter end with a groove 172 therein to receive and restrict the movementof the inlet 52. Left and right lateral finger elements 168 and 170 arepositioned on either side of the plunger 136.

The top, right and left finger elements 166, 168, and 170 have a fingerbase 174 attached to the vertical base surface 124, a finger tip 176extending horizontally from the finger base 174 toward the main carriage78, and an end stop ledge 178 formed between the finger base 174 and thefinger tip 176. Each finger tip 176 being tapered with a narrowedportion facing the main carriage.

Corresponding finger grooves 180 are formed in each side wall 84, 86 forreceiving the left and right lateral finger elements 168, 170,respectively, of the main chassis 122. Each groove 180 has a closed endformed by the outer lips 88 for abutting corresponding finger posts 182formed at outer ends of the finger tips 176.

With reference to FIGS. 10 and 11, in operation the cassette 50 isinserted into top opening 76 of the front carriage assembly 74, when theloader 20 is in the open position. Upon insertion, the cassette 50slides into the main carriage 78 and is loosely secured in place bycassette footing 92. The lateral support 94 of the cassette footing 92restricts the lateral movement of the cassette rim 72; the inner lip 95and the outlet support lip 98 restrict the horizontal movement of thecassette inner surface 68 by engaging the rim 72; and the outlet supportlip 98 fits around and restricts the movement of the cassette outlet 54.

With reference to FIGS. 10, 12 and 13, the main carriage 78 is movablefrom an open position horizontally inwardly with respect to the mainchassis 122 to a closed position to engage the cassette 50 to the fixedseat 162. When the loader 20 is loaded with a cassette 50 and closed,the left and right lateral finger elements 168, 170 are received withinthe finger grooves 180 between the side walls 84, 86 and the cassette50. The cassette footing 92 permits the cassette 50 to adjust itsposition within the main carriage 78 while the cassette 50 is beingforced onto the fixed seat 162.

With reference to FIGS. 8 and 14, a rear carriage assembly 190 hasfasteners 192 to connect to fastener receivers 194 formed in side plates196 of the front carriage assembly 74. Each side plate 196 extends fromone of the front fascia 102, 104 towards the rear carriage assembly 190.A clearance opening 195 is formed through each of the side plates 196and a curved notch 197A is formed in each main body 106 for receiving acorresponding curved post 197B which extends horizontally from each ofthe side walls 84 and 86 of the main carriage 78. The sets of curvednotches 197A and posts 197B allow minor movement of the main carriage 78within the side openings 108 of the front fascia 102 and 104.

With reference to FIGS. 5, 8 and 10, additionally, the curved posts 197Ballow the main carriage 78 to “float” with respect to the main chassis122. This floating of the main carriage 78 allows the fixed seat 162 todictate the position of both the main carriage 78 and cassette 50 whenthe main carriage 78 is in the closed position. Thus the main carriage78 has rotational freedom on at least one axis with respect to the mainchassis 122.

While the embodiment described above is directed to rotational freedomon at least one axis, one of ordinary skill in the art will appreciatethat various embodiments that permit rotational freedom on two or eventhree axes may be provided without departing from the present invention.For instance, it is contemplated that the main carriage 78 could beattached to a gimbal system (not shown) which would allow full XYZrotational freedom to the main carriage 78 with respect to the mainchassis 122.

The finger elements 164, 166, 168, and 170 of the fixed seat 162 dictatethe vertical and lateral position of the cassette 50, while carriage isheld against posts 182. Posts 182 are the defining features for theinward/outward location of the cassette 50. The lips 88 of the maincarriage 78 contact the posts 182 and the rim 72 of the cassette 50simultaneously, controlling their registration. The rim 72 and posts 182are both in contact with the same surface of the carriage 50, andtherefore are coincident with each other.

One of ordinary skill in the art will appreciate that variousembodiments of the finger elements 164, 166, 168, and 170 may beprovided without departing from the present invention. For instance,finger element 164 may be provided as a flexible resilient member toprovide an upward biasing force on the cassette 50 while also displacingto accommodate some variance in the positioning of the cassette 50.Similarly, finger element 166 may be a flexible resilient member toprovide a downward biasing force.

With reference to FIGS. 8 and 14, the rear carriage assembly 190includes an actuator 198 connected to the main carriage 78 via the sideplates 196 to automatically move the main carriage 78 from the openposition to the closed position. The actuator 198 is shown as a linearactuator; however other types of drives may be used without departingfrom the present invention. For instance, a cam plate driven by a DCmotor could be used instead of the linear actuator 198 shown here.

With reference to FIGS. 14 and 16, a threaded shaft 202 is driven by theactuator 198. As the shaft 202 turns, a nut 204 is tightened or loosenedalong the length of the shaft 202 (i.e. moves axially). This tighteningor loosening of the nut 204 transfers the rotational drive of theactuator 198 into a linear motion to drive the front carriage assembly74. Left and right plate housings 206 are positioned around the nut 204and contain a slot 208 which receives a pin element 210 of the nut 204.An adapter 212 is located on the shaft 202 to attach the nut 204 to theplate housing 206. A release plate 214 is downwardly biased (i.e. bygravity, spring, or other device) and slidably received within avertical plate slot 216 formed in the plate housing 206. An engagementportion 218 is formed as a hole in the release plate 214 for normallycoupling and slidably engaging the release plate 214 to an annulargroove 215 on the nut adapter 212.

In an emergency, the release plate 214 can be manually uncoupled ordisengaged from the nut adapter 212, thus disengaging the actuator 198from the front carriage assembly 74. A release aperture 220 is formed asa hole in the release plate 214 and is positioned below but connected tothe engagement portion 218. The release aperture 220 has a greaterdiameter than the engagement portion 218. Preferably the releaseaperture 220 and the engagement portion 218 partially overlap, with theengagement portion 218 having a diameter slightly larger than the groove215 and the release aperture 220 having a clearance diametersignificantly larger than the nut adapter 212 adjacent to the groove215. As the release plate 214 is raised, the engagement portion 218 israised out of the groove 215 in the nut adapter 212 and the releaseaperture 220 allows the release plate 214 to be slid over the nutadapter 212, thereby uncoupling or disengaging the plate housing 206 andfront carriage assembly 74 from the actuator 198.

An emergency release element 222 is provided for raising the releaseplate 214 and disengaging the plate housing 206 from the actuator 198.The emergency release element 222 has a finger switch 224 allowing auser to manually pull forward the spring biased emergency releaseelement 222. The emergency release element 222 allows a user to manuallyremove cassette 50 from the pump 10 in cases of pump malfunction or lossof power.

With reference to FIGS. 14 and 17, as the emergency release element 222moves forward, a vertical column 226 having an upper end forming a ramp228 engages a bottom edge 230 of the release plate 214. The verticalcolumn 226 passes between lower legs 232 of the plate housing 206, withthe ramp 228 gradually raising the release plate 214 until the releaseaperture 220 is positioned around or aligned with the nut adapter 212.At the apex of the ramp 228, side tabs 234 extending horizontally fromthe vertical column 226 engage the lower legs of the plate housing 206.

With reference to FIG. 18, once the release plate 214 is raised, theforward motion of the emergency release element 222 causes the side tabs234 to push the plate housing 206 forward. The release aperture 220 isslid over the nut adapter 212, and the plate housing 206 and frontcarriage assembly 74 are moved to the open position disengaged from theactuator 198.

With reference to FIGS. 16 and 19, once the user activates the emergencyrelease element 222, it can then be released. A spring 235 (or otherbiasing device) biases or returns the emergency release element 222 toits normal position, while the plate housing 206 and front carriageassembly 74 remain in the open position and also remain disengaged fromthe actuator 198. The spring biased release plate 214 lowers itself torest on the shaft 202. In this position, the release plate 214 cannot bereengaged to the nut adapter 212.

Further, manually pressing the front carriage assembly 74 to a closedposition while pulling the emergency release element 222 forward willnot reengage the nut adapter 212 as a certain amount of tension betweenthe nut adapter 212 and release plate 214 was released when theemergency release element 222 was originally pulled. This amount ofreleased tension is enough to prevent a user from manually forcing thefront carriage assembly 74 back far enough to register the engagementportion 218 of release plate 214 with the groove 215 in the nut adapter212.

When the actuator 198 originally drove the front carriage assembly 74 toa closed position, the actuator 198 induced the above-mentionedreleasable tension by pulling the main carriage 78 hard against theposts 182. The actuator 198 is driven past the point of initial contactuntil increasing mechanical resistance stalls it or a predeterminedelectrical load is reached. The nut 204 and nut adapter 212 are drivenback as far as possible. In doing so, all of the dimensional slack istaken out of the interconnected chain of components, including but notlimited to the main chassis 122, side chassis 236, 238, rear carriageassembly 190 (actuator 198, shaft 202 and nut 204), side plates 196, andmain carriage 78. These components are placed under tension orcompression, depending on their function, by the pull of the overdrivenactuator 198. The user who tries to reengage the nut adapter 212 andrelease plate 214 would have to manually recreate these conditions inorder to reengage. However, the user cannot reach the internalcomponents such as the actuator 198, threaded shaft 202 and nut 204 toestablish such conditions.

The prevention of manual reengagement between the nut adapter 212 andrelease plate 214 provides a continuous visual indicator that the pump10 is not operational due to the open position of front carriageassembly 74. The prevention of manual reengagement between the adapter212 and release plate 214 also ensures that error signals generated bypump 10 must be addressed prior to recoupling or reengaging the nutadapter 212 and release plate 214 and restarting the pump 10.

Thus, it can be appreciated that no manual closure of the front carriageassembly 74 is possible with the present invention. By pump 10 requiringthe automated closure of front carriage assembly 74, a user is not ableto insert a cassette 50 into a non-operational pump 10. This ensuresthat the full array of detection and safety elements in pump 10 areactive when a cassette 50 is engaged with the pump 10.

With reference to FIG. 20, to reengage the actuator 198 the user mustelectrically drive the actuator 198 forward while simultaneously pullingthe emergency release element 222 forward. This allows the groove 215 ofthe nut adapter 212 to be driven underneath the engagement portion 218of the release element 214. Once the groove 215 of the nut adapter 212is beneath the engagement portion 218, the emergency release element 222can be released. When the emergency release element 222 is released, theengagement portion 218 drops into the groove 215 of the nut adapter 212and reengages the front carriage 74 to the actuator 198.

With reference to FIG. 15, left and right side chassis 236 and 238 housethe pump chassis assembly 120 of FIG. 9 and the rear carriage assembly190 of FIG. 14. A front opening 240 is formed in the side chassis 236and 238 to fit around the main chassis 122. An upper opening 242 isformed in the side chassis 236 and 238 to fit around the motor 142.

A lower channel 244 is formed in the side chassis 236 and 238 to fitaround the manual release finger switch 224. The lower channel 244surrounds the finger switch 224 and is sealed to the manual releaseopening 26 of infuser cover 16, allowing a user to access the fingerswitch 224 from outside the infuser cover 16. A manual release groove246 slidably receives a horizontally flat plate slider 248 of theemergency release element 222, allowing the emergency release element222 to slide back and forth along the manual release groove 246.

An actuator seat 250 is formed in the side chassis 236 and 238 to fitaround the actuator 198 and secure the actuator to the side chassis 236and 238. Rear carriage ports 252 are formed in the side chassis 236 and238 to allow the rear carriage fasteners 192 to pass through the sidechassis 236 and 238 to attach the rear carriage assembly 190 to the sideplates 196 of the front carriage assembly 74. The rear carriage ports252 also allow the rear carriage fasteners 192 to move back and forth asthe actuator 198 drives the plate housing 206. Nut ports 253 slidablyreceive the pin elements 210 of the nut 204 and prevent the nut 204 fromrotating when actuator 198 is activated.

With reference to FIGS. 6, 14 and 15, female fasteners 254 extend fromthe outer surface of side chassis 236 and 238 to secure an infusercircuit board 256 via male fasteners 258.

With reference to FIGS. 6, 9 and 15, side plate channels 260 are formedas paired “L” shaped brackets on the outer surface of side chassis 236and 238. The side plate channels 260 slidably hold the side plates 196of the front carriage assembly 74 as it moves back and forth.Additionally, side plate guides 261 are formed as paired box shapedbumpers adjacent the rear carriage ports 252 on the outer surface ofside chassis 236 and 238. The side plate guides 261 are spaced apart andmay be preferably positioned parallel to one another. The side plateguides 261 are positioned on both the top and bottom of the side plates196 to prevent rotation of the side plates 196 near the rear carriageports 252. These side plate channels 260 and side plate guides 261provide for a straight line insertion of the front carriage assembly 74,which avoids the adverse rotational effects of prior art manual loaders.

Air cam channels 262 formed as paired “L” shaped brackets on the outersurface of side chassis 236 and 238. The air cam channels 262 slidablyhold the air cam plates 154 of the front carriage assembly 74 as itmoves back and forth horizontally. Air cam ports 264 are formed throughthe side chassis 236 and 238 adjacent the air cam channels 262. The aircam ports 264 permit the cam elements 150 of the air sensors 144 tocontact the air cam plates 154.

With reference to FIGS. 6 and 8, a position sensor 266 is attached tothe outer surface of the left side chassis 236. The position sensor 266monitors the position of a slot 268 formed in a position plate 270. Theposition plate 270 is preferably an integral portion of the left sideplate and extends horizontally from the left front fascia 102.Alternatively, the position sensor 266 can monitor the position of anend edge 272 of the position plate 270. By monitoring the position ofthe position plate 270 the position sensor 266 detects the overallposition of the front carriage assembly 74 and the main carriage 78. Theposition sensor 266 shown is a linear pixel array sensor thatcontinuously tracks the position of the slot 268, and does not merelyindicate when the slot 268 has passed a fixed point. It will beunderstood that other devices can be used for the position sensor 266,such as an opto-tachometer sensor.

FIG. 21 is a schematic diagram illustrating the functional components ofthe medical pump 10 used in connection with the disposable cassette 50for delivering a fluid to a patient. A processing unit 280 is includedin pump 10 and performs various operations described in greater detailbelow.

The processing unit 280 is powered by a power supply 281. The processingunit 280 controls the electric motor 142 being energized by the powersupply 281. When energized, the electric motor 142 causes the plunger136 to reciprocate back and forth to periodically down-stroke, causingplunger 136 to press on pumping chamber 66, driving fluid throughcassette 50. On an up-stroke, plunger 136 releases pressure from pumpingchamber 66 and thereby draws fluid from inlet 52 into pumping chamber66.

Likewise the processing unit 280 controls the actuator 198 beingenergized by power supply 281. When energized, the actuator 198 drivesthe front carriage assembly 74 to closed or open positions.

A memory 284 communicates with the processing unit 280 and storesprogram code 286 and data necessary for the processing unit 280 tocalculate and output the operating conditions of pump 10. The processingunit 280 retrieves the program code 286 from memory 284 and applies itto the data received from various sensors and devices of pump 10, aswill be described in more detail below.

The processing unit 280 processes the data from pump 10 to determine allof the following operating conditions: the cassette 50 is incorrectlyoriented, where there is no cassette 50 at all, where the cassette 50 isnot fully seated to the fixed seat 162, when the front carriage assembly74 is in an open or closed position, when a jam in the front carriageassembly 74 is detected, when there is proper flow of fluid through thecassette 50 to the patient, and if air bubbles are entrained in thefluid leaving cassette 50. Once the operating condition has beendetermined, the processing unit 280 can output the operating conditionto display 282, activate indicator window 18, and/or use the determinedoperating condition to adjust operation of the pump 10.

Specifically, processing unit 280 receives data from a plunger pressuresensor 290 operatively associated with the plunger 136. The plungerpressure sensor 290 senses the force on plunger 136 and generates apressure signal based on this force. The plunger pressure sensor 290communicates with the processing unit 280, sending the pressure signalto the processing unit 280 for use in determining operating conditionsof pump 10.

The processing unit 280 receives an array of pressure data sensed fromthe cassette inner surface 68 determined by the plunger pressure sensor290 and inlet and outlet pressure sensors 128 and 132. The processor 280combines the pressure data from the plunger pressure sensor 290 withdata from inlet and outlet pressure sensors 128 and 132 to provide onedetermination as to the correct or incorrect positioning of cassette 50.In normal operation, this array of pressure data falls within anexpected range and the processing unit 280 determines that propercassette loading has occurred. Where the cassette 50 is incorrectlyoriented (backwards or upside down, for instance) or where the cassette50 is not fully seated to the fixed seat 162, the array of pressure datafalls outside the expected range and the processing unit 280 determinesthat improper cassette loading has occurred.

Further, once the cassette 50 is fully seated correctly and pumpingoperation begins, the array of pressure data is analyzed by theprocessing unit 280 to determine proper flow of fluid through thecassette 50 to the patient. In one use, the processing unit 280 usesthis pressure signal from plunger pressure sensor 290 to determine thatthe cassette is properly pressing on the plunger 136 and activates theplunger 136 to begin pumping the cassette 50. In another use, theprocessing unit 280 uses this pressure signal from inlet pressure sensor128 to determine if fluid is being supplied to the cassette 50. In afurther use, the processing unit 280 uses this pressure signal fromoutlet pressure sensor 132 to determine the overall fluid pressure beingdelivered to the patient.

Similarly, the processing unit 280 determines the orientation andpresence of cassette 50 by processing data received from the orientationsensor 140. The detection of the presence or absence of flow stop 70 isused to align the cassette 50 as well as monitor the orientation of thecassette 50. In normal operation, this distance data falls within anexpected range for the distance between the orientation sensor and flowstop 70, and the processing unit 280 determines that proper cassetteloading has occurred. Where the cassette 50 is incorrectly oriented(backwards or upside down, for instance), where there is no cassette atall, or where the cassette 50 is not fully seated to the fixed seat 162,the distance data falls outside the expected range and the processingunit 280 determines that improper proper cassette loading has occurred.

Additionally, once the processing unit 280 processes data received fromthe orientation sensor 140 to determine the presence of a properlyloaded cassette 50 in open front carriage assembly 74, the processingunit 280 will automatically close front carriage assembly 74 after agiven period of time and without a direct user command. This timedclosure of front carriage assembly 74 prevents free flow of fluidthrough the cassette 50 as the flow stop post 143 engages and closes theflow stop 70 by forcing the flow stop 70 to a closed position, once thefront carriage assembly 74 is closed.

Further, the processing unit 280 can process data received from theorientation sensor 140 to determine if the flow stop 70 is in an open orclosed position, once the cassette 50 is inserted into open frontcarriage assembly 74. If the processing unit 280 determines that theflow stop 70 is in an open position creating free flow, the processingunit 280 can generate an alarm and/or automatically close front carriageassembly 74 after a given period of time and without a direct usercommand. This prevents free flow of fluid through the cassette 50 as theflow stop post 143 engages and closes the flow stop 70, once the frontcarriage assembly 74 is closed.

The processing unit 280 also receives data from air sensors 144 pressedto effluent tubing 292 attached to the cassette outlet 54. Whensqueezed, the air sensors 144 physically contact the effluent tubing292, the air sensors 144 then excite the effluent tubing 292 withultrasonic waves to get accurate air content data of air containedtherein. In normal operation, this air content data falls within anexpected range, and the processing unit 280 determines that proper fluidflow is in progress. When the air content data falls outside theexpected range, the processing unit 280 determines and indicates thatimproper air content is being delivered to the patient.

The position sensor 266 continuously tracks the position of the slot 268(or end edge 272) portion of the position plate 270. By monitoring theposition of the position plate 270 the position sensor 266 detects theoverall position of the front carriage assembly 74. The processing unit280 is connected to the position sensor 266 to receive position datafrom the position sensor 266. The position data is used by theprocessing unit 280 to determine when the front carriage assembly 74 isin an open or closed position.

In addition to the position data, the processing unit 280 is alsoconnected to the actuator 198 via power supply 281 to receive electricalload data from the actuator 198. The processing unit 280 combines boththe position data and electrical load data to detect jam conditions inthe medical pump 10. In normal operation, the electrical load dataspikes while the position sensor 266 senses the front carriage assembly74 in a fully closed position. This spike in the electrical load data isdue to the actuator 198 being designed to drive past the closedposition. In normal operation this spike in the electrical load dataonly occurs while the position sensor 266 senses the front carriageassembly 74 in a fully closed position, and the processing unit 280determines that proper cassette loading has occurred. Where a foreignobject (such as a finger or hand) is inserted between the front carriageassembly 74 and the main chassis 122, the spike in the electrical loaddata occurs prior to the position sensor 266 sensing the front carriageassembly 74 in a fully closed position, and the processing unit 280determines that that jam conditions have occurred. Additionally, whenthe processing unit 280 determines that jam conditions have occurred,the processing unit 280 reverses the actuator 198 to open the frontcarriage assembly 74.

As discussed above, the processing unit 280 receives various datanecessary for the processing unit 280 to calculate and output theoperating conditions of pump 10. The processing unit 280 retrieves theprogram code 286 from memory 284 and applies it to the data receivedfrom various sensors and devices of pump 10, and generates output. Thisoutput is communicated to the user by the processing unit 280 activatingthe indicator window 18 and/or a display/input device 282.

Specifically, the processing unit 280 activates the light assembly 32 ofthe indicator window 18 to illuminate the main carriage 78 or toilluminate the outer surface 34 providing visual output information ofthe pump status to the user. For instance, the processing unit 280activates the indicator elements 42, to continuously or intermittentlylight up the outer surface 34 of the window unit 18 with various colors.The coloring and/or flashing is used to provide an indication of theoperation conditions of the pump 10. For instance, no lighting wouldindicate that the pump 10 is off; blue flashing indicates the loader 20is being opened to load a cassette; continuous blue lighting indicatesthe cassette is inserted into the loader 20 properly; yellow lightingindicates the cassette is loaded improperly; green lighting indicatesnormal operation once the cassette is loaded and the pump 10 is running;yellow, orange, and/or red lighting indicates various kinds of abnormaloperation once the cassette is loaded and the pump 10 is running. Ofcourse, other condition-indicating color schemes are possible withoutdetracting from the invention.

Additionally, the processing unit 280 activates the light assembly 32 ofthe indicator window 18 to illuminate the main carriage 78. Whenprocessing unit 280 determines that the loader 20 is opened forinsertion of a cassette, the illumination elements 46 are activated toilluminate the area where the cassette is inserted into the pump 10. Theprocessing unit 280 may immediately activate the illumination elements46 or the processing unit 280 may gradually brighten the illuminationelements 46 upon opening of the loader 20.

Likewise, the processing unit 280 communicates with the display/inputdevice 282 and allows the user to receive output from processing unit280 and/or input (data or commands) into the processing unit 280. Whenthe cassette 50 is loaded into the open front carriage assembly 74, auser accesses the display/input device 282 to command the pump 10 toautomatically close the front carriage assembly 74. Likewise, a useraccesses the display/input device 282 to command the pump 10 toautomatically open the front carriage assembly 74 when the cassette 50is to be removed and/or replaced.

Those of ordinary skill in the art will appreciate that display/inputdevice 282 may be provided as a separate display device and a separateinput device. Additionally or multiple separate display devices and/ormultiple separate input devices may be provided. For example, as shownin FIG. 1, the medical pump 10 includes a separate load/eject button 283adjacent the display/input device 282 for commanding the pump 10 toautomatically close the front carriage assembly 74 or to automaticallyopen the front carriage assembly 74 when the cassette 50 is to beremoved and/or replaced. The separate load/eject button 283 may belocated on the infuser mechanism 14 or any other convenient location onthe pump 10.

With reference to FIG. 22, another embodiment of the present inventionis shown with a pair of air sensors 294 including sensor heads 295attached to the near ends of arms 296. The arms 296 are pivotallysecured to the base surface 124 at hinge 298, which comprises pin member299 and a socket 301 for pivotally receiving the pin member 299. Thearms 296 each have a cam slot 300 formed therein that receive cam posts302 located on air sensor cam 304. An air sensor actuator 306 isassociated with the air sensor cam 304 to open and close the air sensors294. Guide elements 308 extend from the base surface 124 to guide themovement of both the arms 296 and the air sensor cam 304.

When the front carriage assembly 74 is traveling to an open position,the processing unit 280 (not shown) activates the air sensor actuator306 (via power supply 281 not shown) to force the air sensor cam 304inward, pivoting the arms 296 about the hinges 298 and moving the sensorheads 295 apart. When the front carriage assembly 74 is traveling to aclosed position, the processing unit 280 (not shown) activates the airsensor actuator 306 to force the air sensor cam 304 to move outward,pivoting the arms 296 about the hinges 298 and moving the sensor heads295 together. The cam slots 300 are designed to include: a rapid travelzone where the cam slot 300 profile is such that the arms 296 closerapidly until the touch the effluent tubing 292 (not shown); acompression zone where the cam slot 300 profile is such that the arms296 are gradually compressed; and a “dwell” zone where the cam slot 300profile is straight and the arms 296 do not close further withadditional air sensor cam 304 motion.

It will be appreciated that carriage loading, orientation sensing andair sensing aspects of the present invention are applicable to othertypes of medical pumps, including but not limited to syringe pumps,reciprocating plunger pumps and peristaltic pumps. For example, thecarriage loader can automatically load a syringe or section of tubingand the air sensors 294 can sense air present in the syringe, tubingconnected thereto, or a section of tubing not associate with a syringe.

Whereas the invention has been shown and described in connection withthe embodiments thereof, it will be understood that many modifications,substitutions, and additions may be made which are within the intendedbroad scope of the following claims. From the foregoing, it can be seenthat the present invention accomplishes at least all of the statedobjectives.

1-21. (canceled)
 22. A medical pump for use with a cassette, comprising:a main chassis having a fixed seat thereon; a main carriage connected tothe main chassis and having an opening therein adapted to receive acassette, the opening forming a carriage footing which restrictsmovement of the cassette within the main carriage, the main carriagebeing movable inwardly with respect to the main chassis from an openposition wherein the main carriage is spaced from the fixed seat to aclosed position to engage the cassette to the fixed seat; and a rearcarriage assembly connected to the main carriage, the rear carriageassembly including a manual release element operatively associated withthe main carriage so that once the manual release element is actuated bya user the main carriage is moved to the open position.
 23. The medicalpump of claim 22, further including an actuator connected to the maincarriage to automatically move the main carriage, wherein the actuatoris connected to the main carriage by the rear carriage assembly, oncethe manual release element is actuated by a user the rear carriageassembly disengages the actuator from the main carriage.
 24. The medicalpump of claim 23, wherein the actuator cannot be reengaged to the maincarriage by manually moving the main carriage horizontally inwardly withrespect to the main chassis.
 25. The medical pump of claim 22, whereinthe manual release element is located remotely from the main carriage.26-31. (canceled)